02660
RACK MOUNTING HINTS
KEEPING
IT
COOL
A power
amplifier
draws energy
from
a primary
electrical
service,
usually a
120volts AC
outlet,
to
drive loudspeaker
systems
with an audio signal. Typically,
only
half
of
the
energy can
be
delivered
to
the
loudspeakers;
remaining
energy is
converted
into
heat,
and must be dissipated
(ventilated)
into
the
air.
Air
circulating
past
heat-producing components absorbs
the
heat
and
carries
it
away. To accomplish this, low and medium power
amplifiers
rely on natural
convection
currents,
while most high power
amplifiers
use
fans.
If
the
air
flow is
impeded,
the
resulting rise in
heat
may cause an
amplifier
to
stop
working or fail.
Circulating
air
currents
must
not
be
cut
off
when installing power amplifiers in
racks.
Power amplifiers using convection cooling
require
spacing between
amplifiers
to
permit
air
flow
between
them.
Power
amplifiers
using
forced-air
cooling, on
the
other
hand, can usually be
stacked
closer
to
each
other
and may
not
need. any blank panel spacing
between
amplifiers.
To
improve
natural
convection
currents
within a
rack,
a
chimney
can
be
created
by
closing
the
back of
the
rack and venting
the
rack
at
the
bottom
to
let
in fresh
air,
and
at
the
top
to
exhaust
hot
air.
Vents should
be
large
rectangular
slots
approximately
19"
wide
by
411
high.
The
rack
cabinet
will require some
type
of blower
if
a
large
air-flow
is required.
It
is
best
to
exhaust
air
from
the
top
of
the
rack
rather
than
to
blow
it
in from
the
bottom.
There will
t>e
less dust and
dirt
in
the
rack
this
way,
if
the
bottom
vent is
sufficiently
large.
INSTALLING THE UNITS
When racks
are
to
be
transported
or
used in mobile
installations,
some
means of
securing
the
rear
of
the
equipment is required. Angle
brackets
attached
either
to
the
bottom,
sides or
rear
panel
are
practical
approaches.
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